Patent US3744042A successfully refreshed from Google Patents.
US3744042A
Expired / Lapsed
US
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Memory protect for magnetic bubble memory
Assignee: HP Inc
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Filing: 1972-05-05
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Granted: 1973-07-03
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Expires: 1992-05-05
Abstract
Abstract A magnetic bubble memory is placed in a canted, static magnetic field to produce a holding bias for the magnetic bubbles in addition to the bubble generating bias. When a rotating magnetic field is applied to move the bubbles, a static bias is also applied to cancel out the holding bias.
Inventors
- 👤 L Cutler
- 👤 R Lacey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:36
CPC Classifications
G; G11; G11C; G11C19/00; G11C19/02; G11C19/08; G11C19/0808; G11C19/0816; G11C19/085
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
132 words
A magnetic bubble memory comprising: a sheet of magnetic material having an easy axis substantially normal to the major surfaces of the sheet; means for producing a first static magnetic field parallel to the easy axis for forming and maintaining magnetic bubbles in the sheet; a pattern of structures on a major surface of the sheet describing a path along that surface for guiding magnetic bubbles formed in the sheet along the path; means for producing a second static magnetic field normal to the easy axis for preventing movement of the magnetic bubbles in the absence of other coplanar magnetic fields; and means for producing a rotating magnetic field in the plane of the major surface for moving the bubbles along the path, includiNg means for canceling the second static magnetic field.
Claim 2
Dependent Claim
132 words
A magnetic bubble memory comprising: a sheet of magnetic material having an easy axis substantially normal to the major surfaces of the sheet; means for producing a first static magnetic field parallel to the easy axis for forming and maintaining magnetic bubbles in the sheet; a pattern of structures on a major surface of the sheet describing a path along that surface for guiding magnetic bubbles formed in the sheet along the path; means for producing a second static magnetic field normal to the easy axis for preventing movement of the magnetic bubbles in the absence of other coplanar magnetic fields; and means for producing a rotating magnetic field in the plane of the major surface for moving the bubbles along the path, includiNg means for canceling the second static magnetic field.
Claim 3
Dependent Claim
37 words
A magnetic bubble memory as in claim 1 wherein the means for producing the first and second magnetic fields comprises a permanent magnet producing a field canted with respect to a major surface of the magnetic material.
Claim 4
Dependent Claim
83 words
A magnetic bubble memory as in claim 2 wherein the means for producing a rotating magnetic field comprises: an A.C. signal generator; a first coil surrounding the magnetic material and connected to the A.C. signal generator; a phase shifter connected to the A.C. signal generator; a second coil, orthogonal to the first coil, surrounding the magnetic material and connected to the phase shifter; and a bucking bias supply connected to the coils to produce a field for canceling the second static magnetic field.
References Cited (Backward Citations)
US3534347A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-02 | 1977-01-01 | 1977-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-02 | 1981-01-01 | 1981-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-02 | 1985-01-01 | 1985-07-03 | $7700.00 | Window Closed / Lapsed |